Powershell 2: How to strip a specific character from a body of ASCII text

It's important to note that the console PS doesn't display Unicode well. You'll have to use the ISE to "see" what's happening. Have a look at this related SO question for some additional reading. You can use the ® character in PS, regardless, if you don't need to watch the script in-action.

In the ISE:

PS C:\Users\jscott> $string = "This string contains the ® character"
PS C:\Users\jscott> $string
This string contains the ® character

PS C:\Users\jscott> $string.Replace("®","")
This string contains the  character

PS C:\Users\jscott> $string ="This ® string ® contains ® many ® characters ®®®®"
PS C:\Users\jscott> $string
This ® string ® contains ® many ® characters ®®®®

PS C:\Users\jscott> $string.Replace("®","")
This  string  contains  many  characters 

To use character code instead of the literal:

PS C:\Users\jscott> $string.Replace("$([char]0x00AE)","")

Per your question update:

You need to convert the ASCII file to Unicode/UTF8 before running it through Import-Csv -- I didn't realize you were using this. Have all look at this and this for other examples.

You may just want to pipe the initial CSV file thought Get-Content or Export-Csv -Encoding Unicode to pre-process the file and make life easier.